The first provisions of Initiative 502, the measure legalizing marijuana for recreational use at the state level, will go into place Dec. 6, pending election certification later this month. On that date, up to one ounce of useable marijuana will be decriminalized and the Driving Under the Influence of Drugs mandate will go into place.

Marijuana-friendly critics of the law, like Anthony Martinelli of the legalization group Sensible Washington, have expressed concern that the per se TetraHydroCannabinol limit—5 nanograms per milliliter of whole blood—will result in unintoxicated citizens being arrested and convicted for driving under the influence.

"Rhetoric and politics aside, the new driving under the influence of drugs policy for THC, which is per se (meaning your blood level, not actual impairment, is the determining factor of guilt), will ensnare innocent individuals, especially patients, and especially those under 21, for whom it's a zero-tolerance policy," Martinelli wrote in a Nov. 6 editorial on Sensible Washington's blog.

"It's not going to be that much different," Enumclaw City Prosecutor Mike Reynolds said. "Alcohol and/or drugs that can cause intoxication are both already covered under state law. You can have a DUI for prescription medication. A DUI for marijuana isn't new. The only complication was in the THC blood level."

Just how long THC—the psychoactive component in marijuana plants responsible for the "high"—stays in the system has been a source of concern for the law's pro-marijuana critics.

"Active THC lingers in the body for days, and we have no home test for individuals to determine if they're below 5 (nanograms per milliliter of whole blood) before they drive," Martinelli wrote in his editorial.

But New Approach Washington, the organization that crafted Initiative 502, argues that the idea that a driver could be intoxicated days after smoking is based on a chemical misunderstanding.

It is true that common drug tests, like those administered by an employer or court monitoring, can detect recent marijuana use days after the fact; even a month for heavy users. But such tests measure carboxy-THC, an inactive chemical that hangs around in the body well after the drug has been metabolized.

But the state blood limit measures active delta-9-THC. In the same plasma study, the average user's active THC levels skyrocketed to 150 milliliters per nanogram shortly after use, before dropping to less than 20 within an hour. Blood levels of active THC gradually decreased to near-zero four hours after use.

"For example, a person who is not a drinker at all may have a little bit and become impaired from that amount. The chemical presence might not be a lot, but because of their ability to drive being impaired, they could still be charged with DUI."

Before a standard suspicion-of-DUI stop, officers first consider whether a vehicle is traveling erratically in a way that might suggest an intoxicated driver. If it is, an officer will initiate a stop and contact the driver, noting any strange behavior, slurred speech or smell of intoxicants.

"There typically is a good indication (if a driver is under the influence of a substance) because they act differently," Bonney Lake Police Chief Dana Powers said. "Typically, if you have the telltale signs, an officer will move on to FSTs."

The Standardized Field Sobriety Test, commonly abbreviated by law enforcement officers as SFSTs or FSTs, is a battery of three tests administered to determine impairment and establish probable cause for an arrest. They are the horizontal gaze nystagmus test—a check for exaggerated involuntary jerking of the eyes as they follow an object side-to-side—the walk and turn test along a straight line, and the one-leg stand. Research sponsored by the National Highway and Traffic Safety Administration has determined that the combined results of the three tests create an accurate idea of intoxication 91 percent of the time.

It's at this point that alcohol and drug-related DUI stops differ.

In a drinking-related DUI or DWI investigation, an officer follows the SFST with a portable breath test to determine whether the driver is in excess of the 0.08 Blood Alcohol Content limit. The portable test provides a presumptive—but not evidentiary—BAC level that factors into an officer's decision whether to arrest a suspect and administer two evidentiary breath tests during booking.

Marijuana and other non-alcohol drugs have no such presumptive test.

"There are an advanced form of SFSTs," Enumclaw Lt. Bob Huebler said. "Officers may decide they're needed on stops where drivers show impairment, but not necessarily intoxication."

The advanced tests, as described by Huebler, examine a host of physical signs of drug use, including respiration and pulse, and require the expertise of a trained Drug Recognition Expert. Certification is a rigorous process that requires demonstrable knowledge of the effects of a whole wide world of drugs, and it's rare for a local department to have one on staff. Enumclaw Police have a DRE on staff, and Bonney Lake calls one in from other Pierce County agencies when needed.

If the criteria for suspicion of drug use are met, police can have the suspect's blood drawn at a medical facility. The blood is extracted to vials provided by Washington State Patrol and submitted to a state lab for analysis. That's true for suspicion of any drug, and is already true for marijuana, Reynolds said; the new THC blood limit simply sets the standard for presumed intoxication.

But a blood level below the legal limit doesn't guarantee protection against charges, according to the text of the law. In cases where a sample—of either THC or alcohol—is obtained more than two hours after the suspect was driving, any result above zero may be used as evidence of sufficient intoxication while behind the wheel.

Additionally, drivers younger than 21 are subject to zero tolerance on THC blood levels, in contrast to the 0.02 blood alcohol limit for minors.

With marijuana DUI law brought closer to that of alcohol, law enforcement's approach is part status quo, part wait-and-see.

"The state is obviously going to have to look at (the law)," Powers said. "You can possess it now. It opens up a lot of questions no one has all the answers to yet. So as we work through this, we'll be paying close attention to case law that arises in the future.

"We'll do our best to work with the state and the county through it all."

Huebler agreed.

"We're keeping our ears to the ground," he said. "Case law guides us and gives us a better idea of things (as cases are decided in court). We're here at the will of the people, and if (recreational marijuana) is what the people want, it's our job to work with that."

The Courier-Herald called Buckley Police Department Officer Kevin Goss, a trained marijuana technician and high-volume DUI arrester, Wednesday regarding the DUID provision of Initiative 502. Goss responded with a voice mail message Thursday morning. He was not sure how Initiative 502 would play out, he said, but he was "sure" DUID arrests would go up once officers had the proper field training.

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